I was wrong trusting 40D's Auto White Balance. I was shooting a girl in a purple t-shirt under the sunlight in a park. Until I learned that the colour did not come out right, it was almost end of the programme. A new assignment I got is to shoot with colour temperature setting for a year. Haha!
Comments
Other than white balance, maybe you can try to use color filter or adjust light bulb color.
A lesson to learn from this, never decorate a purple wedding ^_*